Welding helmets protect a user's eyes and skin from sparks and from potentially vision-damaging ultraviolet and infrared rays. Traditional welding helmets include a fixed shade with a glass lens, which remains darkened at all times. However, traditional welding helmets can be difficult to use because a user may need to frequently lift the helmet to examine a weldment welding joint and/or other work piece and set his position to prepare for welding and then lower the helmet again to perform the weld. This repetitive movement can case neck strain and may quickly fatigue a user.
More advanced auto-darkening helmets include variable controls that adjust the shade of a protective lens by incorporating quick-changing liquid crystal display LCD elements in the protective lens. Auto-darkening helmets include one or more light sensors and are configured to quickly darken to a pre-selected shade. Because a user can see clearly while the helmet is in a lowered position, auto-darkening helmets allow users to examine and set-up a weld in a weldment joint without raising the helmet. This increases a user's comfort and productivity by reducing fatiguing helmet adjustments and allowing more continuous work.
Currently available auto-darkening welding helmets are configured with adjustable settings for toggling between shade ranges. This allows users to adjust the shade of a protective lens based on a particular application. For example, higher shade levels may be appropriate for welding thick materials at high current settings or welding processes such as tungsten inert gas (TIG). On the other hand, lower shade levels may be more appropriate for lower current welding such as metal inert gas (MIG) welding or plasma arc or oxygen acetylene torch cutting to assure adequate visibility of the work piece to control the arc and judge appropriate travel speed.
Currently available auto-darkening welding helmets may also be configured with adjustable delay controls to lengthen or shorten the amount of time it takes for the helmet to return to a particular shade level following the completion of a weld. A relatively short delay setting of about 0.5 seconds may be appropriate to allow a user to move quickly between welds when a weld duration is short, for example, during a tack welding operation. A relatively long delay setting of about two seconds may be more appropriate for performing lengthy welds on thick materials so that the high shade level can be maintained to protect a user from viewing a larger, hotter weld until it has cooled.
Currently available auto-darkening welding helmets may also be configured with an adjustable sensitivity function to adjust the lens switching trigger from light to dark based on the ambient light conditions of the welding environment. For example, when welding outside, it is more appropriate to adjust to a higher setting in order for the lens to sense the arc starting. When welding in a darker area it is more appropriate to lower the sensitivity adjustment to minimize external light sources from inadvertently triggering the lens.
Some currently available auto-darkening welding helmets may include a combination of control input devices such as knobs, dials and push buttons to make adjustments to shade, delay and sensitivity, for example. Available auto-darkening helmets may include either external or internal controls. External controls allow some adjustments to be made while a helmet is being worn by a user. However, currently available helmets do not allow a user to view an indication of the control level being adjusted by an external control while the user wears the helmet in a lowered, operational state. Thus, the user is not provided with feedback to indicate the adjustment level while the helmet is in the lowered adjustment state or a direct indication of what each of the control knobs are as they are not within the user's line of sight. Moreover, some welding helmets with external controls are difficult or impossible to operate by a user wearing bulky user's gloves.
Some available auto-darkening welding helmets include internal controls positioned inside of the helmet that may only be accessed by removing the helmet. Such helmets generally cannot be adjusted while the helmet is being used for a welding operation. Other previously known auto-darkening helmets include internal controls that may be reachable when the helmet is in the lowered operational state but do not allow a user to view an indication of the control level being adjusted while the helmet is in the lowered, operational state for performing a welding operation. The user must estimate an adjustment state based on tactile feel of the control inputs and observed control effect on the lens. Moreover, internal adjustment controls that are reachable from the outside have been too small for practical manipulation by a worker wearing welding gloves. Thus each of the previously known auto-darkening welding helmets require a user to remove the helmet, raise the lens and/or remove welding gloves in order to accurately adjust the control settings.